Reducing Refresh Rate Makes External Monitor Go Blank

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Level 1

49 points

Reducing Refresh Rate Makes External Monitor Go Blank

Just installed MacOS Sonoma on my Mac Mini.

I am sensitive to animation, especially smooth animation, and "Reduce Motion" isn't blocking enough of it. I tried reducing the refresh rate to 30/second to at least help un-smooth the animation. I got an input error on my monitor. I managed to connect via dvi + usb-c, but I can't find a way to revert the refresh rate settings for hdmi.

Is there any way to fix the display settings when they don't work with the monitor?

Mac mini, macOS 14.2

Posted on Dec 15, 2023 9:03 PM

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Answer 1

Marja E Author

Level 1

49 points

Dec 16, 2023 2:43 AM in response to Marja E

After several hours, multiple pram/nvram resets, etc.:

I can get an hdmi connection in MacOS if and only if I also have a dvi connection at the same time. I get a refresh rate option, (Yay!), but setting it back to 50 or 60 doesn't fix this.
I can get an hdmi connection in Linux without the dvi connection. I think the last pram reset might have helped, but I'm not sure how.
I can also get an hdmi connection in the boot sequence. If I hold alt/option during startup, I also get it in the disk selection screen. I use that a lot, becase I'm dual booting. But it drops at the very end before loading MacOS Sonoma.

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Answer 2

Tesserax

Level 10

152,930 points

Dec 15, 2023 10:15 PM in response to Marja E

I'm running macOS Sonoma on my M2 Pro Mac mini. The following is a screen shot of the System Settings > Displays pane with the list of resolutions enabled.

If I pan down lower on this same pane, I can see the option to change the Refresh rate.

If I select the up/down arrows, I get a drop-down menu of multiple refresh rates I can try.

If neither of these are available, then your monitor does not support it.

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Answer 3

Tesserax

Level 10

152,930 points

Dec 15, 2023 9:30 PM in response to Marja E

Most, if not all, monitors have defined resolution settings with corresponding refresh rates. If you attempt to use a setting that it not supported, any number of display issues may occur ... like you are witnessing.

The only potential option is to try out different monitors that support the resolutions you need.

As far as "fix"ing the display settings, you can display the resolutions for this monitor, by going to System Settings > Displays > Advanced. Then enable the "Show resolution as list" option. You should then see a listing of all resolutions that this display can support. Optionally, you can enable the "Show all resolutions" option to include resolutions that the display DOES NOT support to try them out ... but, most likely, they will not work properly.

Similarly, you can change the refresh rate for each resolution on the Displays panel.

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Answer 4

Marja E Author

Level 1

49 points

Dec 16, 2023 1:19 AM in response to Tesserax

Display preferences supported refresh rates before. It had a list including 60, 50, 30, and 25. It worked with 60 and 50. It went blank when I picked 30. It hasn't worked without the dvi cable since.

Now the dvi *sometimes* shows a refresh rate option, sometimes not. If I can get the hdmi to show again-- which requires unplugging and replugging both ends of the hdmi cable and leaving dvi in place-- then the hdmi does not show any refresh rates.

I encounter the same puzzling behavior on a Linux partition and on the Mac recovery partition. I tested with another monitor, so the problem is not with the hdmi port. I can't switch to that other monitor, because it's too bright.

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Answer 5

Marja E Author

Level 1

49 points

Dec 17, 2023 12:14 PM in response to Marja E

SOLVED!

For an internal boot drive, an nvram reset should work.

For an external boot drive, deleting /Library/Preferences/com.apple.windowserver.plist and ~/Library/Preferences.ByHost//Library/Preferences/com.apple.windowserver[number].plist should work.

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Answer 6

Marja E Author

Level 1

49 points

Dec 15, 2023 9:34 PM in response to Tesserax

The refresh rate options have disappeared from the Displays preferences.

The resolution options do not have anything about refresh rates, why would they?

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Answer 7

Tesserax

Level 10

152,930 points

Dec 16, 2023 10:31 AM in response to Marja E

Sorry, but I really don't have a means to try this out for you, and as such, cannot provide you with a working solution. Maybe someone else here can and will chime in with how they did it. Good luck!

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